For the past year, the aid group has been piloting a food security surveillance system in Kenya's arid northeast, based on household questionnaires conducted every three months. And in Uganda, after a similar two-year project, it is developing national guidelines to monitor food security with the health ministry.

Funding is an obstacle. Shifting to a more responsive system will require political commitment and long-term financial resources, but rich governments and U.N. agencies tend to offer money on a short timeframe.

'As long as something like this is donor-driven, the sustainability becomes questionable,' Nyasani said.

Ultimately, however, it is not data, but action, that makes a difference.

Saul Guerrero, evaluations adviser with Action Against Hunger, said aid workers detected warning signs months before the onset of last year's severe hunger crisis in the Horn of Africa, where some 13 million people needed food aid because of a regional drought and conflict in Somalia.

'Whoever tells you the data let us down doesn't know what they are talking about," he said. 'It was the final bit that didn't work - turning data into policy. This is the question no one has the full answer to.'"